title: Proteomic analysis of the membrane palmitoylated protein-4 (MPP4)-associated protein complex in the retina.
abstract: Membrane palmitoylated protein-4 (MPP4) is a retina-specific scaffolding protein of the membrane-associated guanylate kinase family that has been implicated in organizing presynaptic protein complexes in the photoreceptor ribbon synapse. To isolate the components of this complex we applied a proteomic approach based on immunoaffinity chromatography with a monoclonal anti-MPP4 antibody followed by two-dimensional electrophoresis and mass spectrometry. Among the identified molecules were previously reported proteins of the MPP4 scaffolding complex including adaptor proteins Veli3 and Psd95. Here we demonstrate a selective association between MPP4 and the Psd95-beta isoform that is mediated by interaction of their N-terminal L27 domains. In addition, we have identified recoverin and Hsc70 as novel associated proteins of the MPP4 multiprotein complex in the retina. This study demonstrates the utility of anti-MPP4 antibody precipitation for the elucidation of the MPP4-associated protein complex, which is essential in understanding its precise role in signal transmission at the photoreceptor synapse.
authors.affiliation: Institute of Human Genetics, University of Regensburg, Regensburg, Germany.
authors.forename: Johanna R
authors.initials: JR
authors.lastname: Förster
authors.forename: Günter
authors.initials: G
authors.lastname: Lochnit
authors.forename: Heidi
authors.initials: H
authors.lastname: Stöhr
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000302:isolation & purification / Q000378:metabolism; D000818:Animals; D002417:Cattle; D000076122:Disks Large Homolog 4 Protein; D015180:Electrophoresis, Gel, Two-Dimensional / Q000379:methods; D005136:Eye Proteins / Q000302:isolation & purification* / Q000378:metabolism; D051528:Guanylate Kinases; D050883:HSC70 Heat-Shock Proteins / Q000032:analysis; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D051379:Mice; D020033:Protein Isoforms / Q000378:metabolism; D040901:Proteomics / Q000379:methods; D051603:Recoverin / Q000032:analysis; D012160:Retina / Q000737:chemistry* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000076122:Disks Large Homolog 4 Protein; C501447:Dlg4 protein, mouse; D005136:Eye Proteins; D050883:HSC70 Heat-Shock Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D020033:Protein Isoforms; C496732:Rcvrn protein, mouse; D051603:Recoverin; D051528:Guanylate Kinases